Discriminated record question

[Mark.Doherty@uk.thalesgroup.com (Mark Doherty)]

Why does the following raise a constraint error on the declaration of
'B'.

I would not expect the declarations of 'A' or 'B' to raise a
constraint error.

If the compiler is right what, is the subtle difference between them
that allows 'A' not to raise the constraint error.

I am using Rational 3.2 compiler (PowerPC and Sun Solaris)



procedure Test is
    type A_Type (Text_Size : Natural := 0) is
       record
            Text : String (1 .. 0);
        end record;
    A : A_Type;

    type B_Type (Text_Size : Natural := 0) is
        record
            Text : String (1 .. Text_Size);
        end record;

    B : B_Type;  

begin
    null;
end Test;